PSI - Issue 84

Arianna Lupattelli et al. / Procedia Structural Integrity 84 (2026) 845–851

846

1. Introduction Transportation infrastructures are increasingly affected by aging and progressive degradation due to mechanical fatigue and long-term environmental exposure. As a consequence, a large number of bridges and viaducts are currently approaching or exceeding their design service life, making structural retrofitting interventions necessary to ensure safety and serviceability (Messore et al., 2020). In bridge maintenance practice, foundation strengthening is frequently required, and micropiles are among the most commonly adopted solutions due to their versatility and effectiveness (Bruce, 1997; Tanzini, 2004). In parallel, roadway pavements are severely impacted by extreme climatic conditions, particularly during winter. Snow and ice accumulation significantly reduce traffic safety and accelerate pavement deterioration (Fu et al., 2010). Conventional snow-control methods based on chemical deicers and mechanical removal are associated with environmental impacts and long-term damage to infrastructure (Kenzhebayeva et al., 2021). To overcome these limitations, some sustainable alternatives have been investigated, such as Hydronic Heated Pavement Systems (HHPS) supplied by renewable energy sources (Johnsson & Adl-Zarrabi, 2019; Gruber et al., 2023; Liu et al., 2025). In this context, low-enthalpy geothermal energy represents a stable and reliable heat source for infrastructure applications (Adl-Zarrabi et al., 2016; Bowers, 2016; Kong et al., 2019; Ghalandari et al., 2021). Energy geostructures, such as energy piles, integrate heat exchanger pipes within foundation elements, allowing the simultaneous fulfilment of structural and thermal functions (Brandl, 2006, Salciarini et al., 2026). Numerous studies have demonstrated the thermo-mechanical performance of energy piles, mainly with reference to new constructions and building energy supply systems (Laloui et al., 2006; Batini et al., 2015; Bourne-Webb et al., 2022; Lupattelli et al., 2023b; Lupattelli et al., 2024). However, their application to the retrofitting of existing foundations remains limited, despite the fact that many bridge rehabilitation projects already involve foundation interventions. Within this framework, the thermal activation of micropiles—referred to as Energy Micropiles (EMPs)—offers a promising and innovative solution that combines structural reinforcement with renewable energy exploitation (Ronchi et al., 2018; Salciarini & Cecinato, 2021; Kong et al., 2021; Cecinato & Salciarini, 2022; Lupattelli et al., 2023a; Gerola et al., 2023). This study investigates the feasibility of using EMPs integrated into bridge abutments to supply geothermal energy for hydronic pavement snow-melting systems. Finite element simulations are performed to analyze the coupled thermo-mechanical behavior of the soil–foundation system, highlighting the potential of this dual-purpose retrofitting approach to enhance both structural safety and pavement temperature regulation. 2. Theoretical framework In this study, a numerical approach was employed to evaluate the energy performance of the system during snow melting scenario. First, the heat extraction rate of the EMPs, qₚ (W/m²) , was assessed through numerical simulations under realistic operational conditions, providing insight into the efficiency of the system in transferring thermal energy to and from the ground. Secondly, the results were compared against the required thermal load q₀, heat (W/m²) to verify whether net energy extraction could satisfy the system demand. The steady-state energy balance of the bridge deck for the total heat flux required at the upper surface of a snow-melting paved surface during snowfall, as described by ASHRAE (Chapman & Katunich, 1956) is expressed in Eq. (1): 0,ℎ = + + ( ℎ + ) (1) where q s (W/m 2 ) is the sensible heat flux, q m (W/m 2 ) the latent heat flux, q h (W/m 2 ) the convective and radiative heat flux from snow-free surface, q e (W/m 2 ) the heat flux of evaporation, and A r the snow-free area ratio. 3. Numerical analysis A two-dimensional symmetric plane-strain finite element model was developed to simulate a longitudinal section of the viaduct foundation supported by micropiles (Fig. 2). The foundation consists of a reinforced concrete slab supported by 11 micropiles, each 0.20 m in diameter, and 15 m in length, arranged with a center-to-center spacing